Equivalent circuit of controllable commutation converter and control method thereof

Abstract

The invention provides an equivalent circuit of a controllable commutation converter and a control method thereof, the equivalent circuit comprises a first simulation module, a second simulation module, a saturable reactor and a power assembly, the power assembly comprises a semiconductor device, the first simulation module comprises a first charging unit and a first discharging unit, the first charging unit is used for charging the first discharging unit, and the second simulation module comprises a second charging unit and a second discharging unit. The first discharge unit is used for discharging to the second simulation module through the saturable reactor so as to simulate discharge of lightning arresters connected in parallel to two ends of a single converter valve in the controllable commutation converter; the second simulation module comprises a second charging unit and a second discharging unit, the second charging unit is used for charging the second discharging unit, and the second discharging unit is used for discharging the semiconductor device so as to simulate the discharge current of the lightning arrester connected in parallel to the two ends of the semiconductor device in the converter valve; the problem that the aperiodic trigger working condition of simultaneous discharge of two lightning arresters in the hybrid controllable commutation converter cannot be accurately simulated is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to an equivalent circuit of a controllable commutation converter and a control method thereof. BACKGROUND

[0002] The hybrid controllable commutation converter contains two types of arresters, a device-level arrester is connected in parallel to the two ends of the device to achieve amplitude limiting and voltage equalization, and a valve arrester is connected in parallel to the two sides of a single valve to protect the entire single valve. In the non-periodic triggering process, the valve arrester and the device-level arrester simultaneously discharge, and the arrester connected in parallel to the two ends of the device does not discharge through the saturable reactor, but directly discharges to the power electronic device, which cannot simulate the process of the arrester connected in parallel to the two ends of the power electronic device directly discharging to the power electronic device. SUMMARY

[0003] The main purpose of the present application is to provide an equivalent circuit of a controllable commutation converter and a control method thereof, so as to at least solve the problem that the non-periodic triggering condition of the two types of arresters simultaneously discharging in the hybrid controllable commutation converter cannot be accurately simulated in the related art.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an equivalent circuit of a controllable commutation converter is provided, comprising: a first simulation module, a second simulation module, a saturable reactor and a power component, wherein the power component comprises a semiconductor device, the first simulation module comprises a first charging unit and a first discharging unit, the first end of the first charging unit is electrically connected with the first discharging unit, the first end of the first charging unit is electrically connected with the second end of the first discharging unit, the first end of the first discharging unit is electrically connected with the first end of the saturable reactor, the first charging unit is used for charging the first discharging unit, and the first discharging unit is used for discharging to the second simulation module through the saturable reactor, so as to simulate the discharge of the arrester connected in parallel to the two ends of a single converter valve in the controllable commutation converter; the second simulation module comprises a second charging unit and a second discharging unit, wherein the power component is connected in parallel with the second charging unit, the power component is connected in parallel with the second discharging unit, the first end of the power component is electrically connected with the first end of the second discharging unit and the second end of the saturable reactor respectively, the second end of the power component is electrically connected with the second end of the first discharging unit, the second end of the second discharging unit and the second end of the second charging unit respectively, the first end of the second charging unit is electrically connected with the second discharging unit, the second charging unit is used for charging the second discharging unit, and the second discharging unit is used for discharging to the semiconductor device, so as to simulate the discharge of the arrester connected in parallel to the two ends of the semiconductor device in the converter valve.

[0005] Optionally, the first charging unit comprises a first charging device and a first switch, two ends of the first charging device are electrically connected with a first end of the first switch and a second end of the first discharging unit respectively, and a second end of the first switch is connected with a first end of the first discharging unit.

[0006] Optionally, the first discharging unit comprises a first energy compensation capacitor, a second switch and a first discharging resistor, a first end of the first energy compensation capacitor is connected with a first end of the first charging unit and a first end of the first discharging resistor respectively, a second end of the first energy compensation capacitor is electrically connected with a second end of the first charging unit, a second end of the power component and a second end of the second discharging unit respectively, and a second end of the second switch is electrically connected with a first end of the saturable reactor.

[0007] Optionally, the second discharging unit comprises a second energy compensation capacitor, a third switch and a second discharging resistor, a first end of the second discharging resistor is electrically connected with a first end of the power component and a second end of the saturable reactor respectively, a second end of the second discharging resistor is connected with a first end of the third switch, a second end of the third switch is connected with a first end of the second energy compensation capacitor and a first end of the second charging unit respectively, and a second end of the second energy compensation capacitor is electrically connected with a second end of the power component and a second end of the second charging unit.

[0008] Optionally, the second charging unit comprises a second charging device and a fourth switch, two ends of the fourth switch are electrically connected with the second discharging unit and a first end of the second charging device respectively, and a second end of the second charging device is electrically connected with a second end of the second discharging unit and a second end of the power component.

[0009] Optionally, the equivalent circuit further comprises a current establishing module, the current establishing module comprises a third charging unit and a third discharging unit, a first end of the third discharging unit is electrically connected with a first end of the saturable reactor and a first end of the first discharging unit respectively, a second end of the third discharging unit is electrically connected with a second end of the saturable reactor and a second end of the third charging unit respectively, and a first end of the third charging unit is electrically connected with the third discharging unit.

[0010] Optionally, the third charging unit comprises a third charging device and a fifth switch, two ends of the fifth switch are connected with a first end of the third charging device and the third discharging unit respectively, and a second end of the third charging device is electrically connected with a second end of the third discharging unit and a second end of the saturable reactor.

[0011] Optionally, the third discharging unit comprises a third energy compensation capacitor, a third discharging resistor, a sixth switch, a first inductor, a fourth discharging resistor and a seventh switch, wherein the third discharging resistor and the sixth switch are connected in series, the branch of the third discharging resistor and the sixth switch is connected in parallel with the third energy compensation capacitor, the first end of the first inductor is electrically connected with the first end of the saturable reactor and the first end of the first discharging unit respectively, the second end of the first inductor is electrically connected with the first end of the fourth discharging resistor, and the two ends of the seventh switch are electrically connected with the second end of the fourth discharging resistor and the first end of the third energy compensation capacitor respectively.

[0012] According to another aspect of the present application, a control method of an equivalent circuit of a controllable commutation converter is provided, for controlling the equivalent circuit of the controllable commutation converter, the control method comprising: controlling a first charging unit of a first simulation module of the equivalent circuit to be turned on, so as to charge the first charging unit to a first discharging unit of the first simulation module; controlling a second charging unit of a second simulation module of the equivalent circuit to be turned on, so as to charge the second charging unit to a second discharging unit of the second simulation module; controlling the first discharging unit and the second discharging unit to be turned on at the same time, so as to make the first discharging unit discharge to a power component through a saturable reactor of the equivalent circuit, to simulate the current leakage of the lightning arrester connected in parallel between the two ends of a single converter valve in the controllable commutation converter, and make the second discharging unit discharge to a power component of the second simulation module, to simulate the current leakage of the lightning arrester connected in parallel between the two ends of the semiconductor device in the controllable commutation converter.

[0013] By applying the technical solution of the present application, the first simulation module and the second simulation module are arranged in the equivalent circuit, when the power component of the second simulation module is not triggered, the first charging unit of the first simulation module is used to charge the first discharging unit of the first simulation module, after the charging is completed, when the power component is turned on, the first discharging unit of the first simulation module discharges to the power component, to simulate the current leakage of the valve-type lightning arrester. The second charging unit and the second discharging unit in the second simulation module are connected in parallel with the power component respectively, the charging and discharging of the simulated device-level lightning arrester can be controlled independently, and the accurate simulation of the device-level lightning arrester is provided. In this way, the current leakage process of the device-level lightning arrester can be synchronized with and independent of the process of the valve-type lightning arrester, and the overall controllability and accuracy of the test are improved. Through the two independent and cooperative modules, the current leakage characteristics of the simulated device-level lightning arrester and the valve-type lightning arrester are realized, it can be ensured that each module can accurately match the actual working condition, and the test result deviation caused by the mutual influence between the modules in the traditional test method is avoided, the actual stress working condition of the hybrid controllable commutation converter in the non-periodic triggering process is effectively reproduced, and the fidelity and reliability of the test result are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the application and, together with the description, serve to explain the application. In the drawings:

[0015] Figure 1 An equivalent circuit structure block diagram of a controllable commutation converter provided in an embodiment of the application is shown;

[0016] Figure 2 A structure schematic diagram of a controllable commutation converter provided in an embodiment of the application is shown;

[0017] Figure 3 An equivalent circuit structure block diagram of another controllable commutation converter provided in an embodiment of the application is shown;

[0018] Figure 4 An equivalent circuit structure block diagram of a controllable commutation converter provided in an embodiment of the application is shown;

[0019] Figure 5 A schematic diagram of equivalent circuit simulation bleed of a controllable commutation converter provided in an embodiment of the application is shown;

[0020] Figure 6 A flowchart of a control method of an equivalent circuit of a controllable commutation converter provided in an embodiment of the application is shown.

[0021] Wherein, the above drawings include the following reference signs:

[0022] 1, voltage impulse source; 2, commutation inductance; 3, stray capacitance; 4, preset saturation reactor; 5, device assembly; 6, valve-type surge arrester; 7, power device; 8, buffer circuit capacitance; 9, buffer circuit resistance; 10, first simulation module; 11, first charging unit; 111, first charging device; 112, first switch; 12, first discharging unit; 121, first energy supplementing capacitance; 122, second switch; 123, first discharging resistance; 13, direct current resistance; 14, device level surge arrester; 20, second simulation module; 30, saturation reactor; 40, power assembly; 21, second charging unit; 211, second charging device; 212, fourth switch; 22, second discharging unit; 221, second energy supplementing capacitance; 222, third switch; 223, second discharging resistance; 50, current establishment module; 51, third charging unit; 511, third charging device; 512, fifth switch; 52, third discharging unit; 521, third energy supplementing capacitance; 522, third discharging resistance; 523, sixth switch; 524, first inductance; 525, fourth discharging resistance; 526, seventh switch. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0024] In order for those skilled in the technical field to better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0025] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0026] As introduced in the background, in the related art, in the non-periodic triggering process, the valve arrester and the device-level arrester discharge at the same time, and the arrester parallelly connected at both ends of the device does not discharge through the saturable reactor, but directly discharges to the power electronic device, which cannot simulate the process of the arrester parallelly connected at both ends of the power electronic device directly discharging to the power electronic device. In order to solve the problem that the non-periodic triggering condition of the simultaneous discharge of the two types of arrester in the hybrid controllable commutation converter cannot be accurately simulated, the embodiments of the present application provide an equivalent circuit of a controllable commutation converter and a control method thereof.

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application.

[0028] According to an aspect of the embodiments of the present application, as Figure 1As shown, an equivalent circuit of a controllable commutation converter is provided, including: a first simulation module 10, a second simulation module 20, a saturated reactor 30, and a power component 40. The first simulation module 10 includes a first charging unit 11 and a first discharging unit 12. A first terminal of the first charging unit 11 is electrically connected to the first discharging unit 12, and a second terminal of the first charging unit 11 is electrically connected to the second terminal of the first discharging unit 12. A first terminal of the first discharging unit 12 is electrically connected to the first terminal of the saturated reactor 30. The first charging unit 11 charges the first discharging unit 12, and the first discharging unit 12 discharges through the saturated reactor 30 to the second simulation module 20, simulating the leakage current of a surge arrester connected in parallel across a single converter valve in the controllable commutation converter. The simulation module 20 includes a second charging unit 21 and a second discharging unit 22. The power component 40 is connected in parallel with the second charging unit 21 and the second discharging unit 22. The first end of the power component 40 is electrically connected to the first end of the second discharging unit 22 and the second end of the saturated reactor 30, respectively. The second end of the power component 40 is electrically connected to the second end of the first discharging unit 12, the second end of the second discharging unit 22, and the second end of the second charging unit 21, respectively. The first end of the second charging unit 21 is electrically connected to the second discharging unit 22. The second charging unit 21 is used to charge the second discharging unit 22, and the second discharging unit 22 is used to discharge to the power component 40 to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the converter valve.

[0029] By setting up a first simulation module and a second simulation module in the equivalent circuit, when the power component of the second simulation module is not triggered, the first charging unit of the first simulation module charges the first discharging unit of the first simulation module. After charging is completed, when the power component is turned on, the first discharging unit of the first simulation module discharges current to the power component, simulating the discharge of a valve-type surge arrester. The second simulation module includes a second charging unit and a second discharging unit connected in parallel with the power component, which can independently control the charging and discharging of the device-level surge arrester, providing accurate simulation of the device-level surge arrester. This allows the discharge process of the device-level surge arrester to be synchronized and independent with the process of the valve-type surge arrester, improving the overall controllability and accuracy of the test. Through two independent and coordinated modules, the discharge characteristics of the device-level surge arrester and the discharge characteristics of the valve-type surge arrester are simulated, ensuring that each module can accurately match the actual operating conditions, avoiding the test result deviation caused by the mutual influence between modules in traditional test methods, effectively reproducing the actual stress conditions of the hybrid controllable commutation converter in the non-periodic triggering process, and significantly improving the fidelity and reliability of the test results.

[0030] In the above embodiment, the non-periodic triggering working condition refers to that during the operation impact process of the hybrid controllable commutation converter, the power device is in the off state and suffers from excessively high voltage, and in order to avoid damage to the power device, the power device needs to be triggered to be turned on to protect the device. As shown in Figure 2 The hybrid controllable commutation converter mainly includes an operating voltage impact source 1, a commutation inductance 2, a stray capacitance 3, a preset saturation reactor 4, a device component 5, a valve-type arrester 6, the device component 5 includes a power device 7, a buffer circuit capacitance 8, a buffer circuit resistance 9, a direct current resistance 13, and a device-level arrester 14. The operating voltage impact source 1 discharges, the valve-type arrester 6 and the device-level arrester 14 establish a large current, the power device 7 (in this application, a semiconductor device in the power component) is triggered after meeting the power electronic triggering condition, and the valve-type arrester 6 and the device-level arrester 14 simultaneously discharge to the power device 7. The device-level arrester connected in parallel across the power device 7 does not discharge through the saturation reactor, but directly discharges to the semiconductor device. However, in the previous equivalent test circuit, the capacitance discharge is all discharged through the saturation reactor, and the current rising rate is limited by the saturation reactor, and the process of the arrester connected in parallel across the power electronic device directly discharging to the power electronic device cannot be simulated. According to the equivalent circuit of the present application, the valve-type arrester and the device-level arrester can simultaneously discharge to the semiconductor device, and the inductance state of the saturation reactor and the effect of limiting the current rising rate when the device is triggered can be accurately simulated, and thus the discharge characteristics of the valve-type arrester and the device-level arrester can be reliably simulated.

[0031] In some optional embodiments, as shown in Figure 3 and Figure 4 The first charging unit includes a first charging device 111 and a first switch 112, the two ends of the first charging device 111 are respectively electrically connected with the first end of the first switch 112 and the second end of the first discharging unit 12, and the second end of the first switch 112 is electrically connected with the first discharging unit 12. The first charging device 111 provides the required high voltage, and the first switch 112 is used to control the charging current and process. The first charging device 111 charges the first discharging unit 12 through the first switch 112, after the charging is completed, the first discharging unit 12 is discharged through the saturation reactor 30 to the power component 40 by triggering the first discharging unit 12 discharge switch, and the current discharge process of the valve arrester to the power electronic device is simulated. The voltage output of the first charging device 111 can be adjusted, so that the response of the arrester under the actual working condition can be accurately copied.

[0032] In some optional embodiments, as shown in Figure 3 and Figure 4As shown, the first discharging unit includes a first energy compensation capacitor 121, a second switch 122 and a first discharging resistor 123, the first end of the first energy compensation capacitor 121 is connected with the first end of the first charging unit and the first end of the first discharging resistor 123 respectively, the second end of the first discharging resistor 123 is connected with the first end of the second switch 122, the second end of the first energy compensation capacitor 121 is connected with the second end of the first charging unit 11, the second end of the power assembly 40 and the second end of the second discharging unit 22 respectively, and the second end of the second switch 122 is connected with the first end of the saturable reactor 30. After the charging is completed, the energy stored in the first energy compensation capacitor 121 can be rapidly released by the first discharging resistor 123 and the opening of the second switch 122, so that the non-periodic current discharge of the valve lightning arrester can be effectively simulated and controlled, and the current discharge of the valve lightning arrester is simulated. This structure ensures that the current can flow along the correct path, simulating the current distribution under actual working conditions.

[0033] In some optional embodiments, as shown in Figure 3 and Figure 4 As shown, the second charging unit includes a second charging device 211 and a fourth switch 212, wherein the two ends of the fourth switch 212 are respectively connected with the second discharging unit and the first end of the second charging device 211, and the second end of the second charging device 211 is connected with the second end of the second discharging unit and the second end of the power assembly respectively. The second charging device 211 charges the second discharging unit through the fourth switch 212, and after the charging is completed, the second discharging unit directly discharges to the power assembly through the device discharging resistor. The above-mentioned second charging unit can ensure that the second discharging unit can be charged to a specific voltage to simulate the current discharge of the device-level lightning arrester. The second charging device 211 provides the required voltage, and the fourth switch 212 is used to regulate the charging current and process, thereby realizing the high simulation of the current discharge characteristics of the device-level lightning arrester.

[0034] In some optional embodiments, as shown in Figure 3 and Figure 4As shown, the second discharge unit includes a second energy-replenishing capacitor 221, a third switch 222, and a second discharge resistor 223. The first terminal of the second discharge resistor 223 is electrically connected to the first terminal of the power component and the second terminal of the saturated reactor 30, respectively. The second terminal of the second discharge resistor 223 is connected to the first terminal of the third switch 222. The second terminal of the third switch 222 is connected to the first terminal of the second energy-replenishing capacitor 221 and the first terminal of the second charging unit, respectively. The second energy-replenishing capacitor 221, by controlling the opening of the third switch 222, simulates the current leakage of a device-level surge arrester, directly discharging current to the power component. The second discharge resistor 223 is used to adjust the current steepness and peak value of the leakage current, ensuring that the response of the device-level surge arrester under different operating conditions can be accurately reproduced.

[0035] In cases where it is still necessary to simulate the current of the saturated reactor, in some alternative implementations, such as Figure 4 As shown, the equivalent circuit also includes a current establishment module 50, which includes a third charging unit 51 and a third discharging unit 52. The first end of the third discharging unit 52 is electrically connected to the first end of the saturated reactor 30 and the first end of the first discharging unit, respectively. The second end of the third discharging unit 52 is electrically connected to the second end of the saturated reactor 30 and the second end of the third charging unit 51, respectively. The first end of the third charging unit 51 is electrically connected to the third discharging unit 52. The current establishment module 50 can establish the current in the equivalent circuit before the power component 40 is triggered. This allows for accurate simulation of the current established by the saturated reactor 30 in the hybrid controllable commutator under different insulation coordination strategies for the device surge arrester and the inductance state it exhibits when turned on. Under different insulation coordination strategies for the surge arrester and the valve surge arrester, the current on the saturated reactor is different when the device is triggered. The inductance of the saturated reactor 30 changes with the current magnitude. The larger the current, the smaller the inductance of the saturated reactor 30. When a certain value is exceeded, the inductance of the saturated reactor 30 becomes only an air core inductance. Therefore, based on the insulation coordination of the two surge arresters, the current established by the saturated reactor 30 when the device is triggered can be determined. The corresponding current can be applied to the saturated reactor 30 through the current establishment loop.

[0036] The layout of the third charging unit 51, the third discharging unit 52 and the saturable reactor 30 ensures that the required preset current of the saturable reactor 30 can be established and maintained before the semiconductor device is triggered, and the energy can be released along a predetermined path after the triggering. After the preset current is set, the inductance of the saturable reactor 30 changes according to the actual situation, so that the working conditions of the converter valve under different inductances can be simulated. If the working condition of the converter valve is that the saturable reactor 30 has not established current, the preset current can not be established during simulation, and the saturable reactor 30 is in a large inductance state. The current establishment module can enable the equivalent circuit to simulate the inductance of the saturable reactor when the device is triggered under different current conditions of the saturable reactor under different insulation coordination strategies of the arrester and the valve arrester, and the application scenarios are more extensive, and the application of the equivalent circuit is more flexible.

[0037] In some optional embodiments, as shown in Figure 4 The third charging unit 51 includes a third charging device 511 and a fifth switch 512, and the two ends of the fifth switch 512 are respectively connected with the first end of the third charging device 511 and the third discharging unit. The second end of the third charging device 511 is respectively electrically connected with the second end of the third discharging unit and the second end of the saturable reactor 30. The third charging device 511 charges the third energy compensation capacitor 521 through the fifth switch 512, and after the charging is completed, the third energy compensation capacitor 521 discharges to the saturable reactor 30 through the inductance and the through-flow switch, so as to establish the required preset current before the power assembly is triggered. By adjusting the voltage of the third charging device 511, the charging voltage of the saturable reactor can be accurately adjusted, and by controlling the fifth switch 512, whether the current is discharged can be controlled.

[0038] In some optional embodiments, as shown in Figure 4As shown, the third discharge unit 52 comprises a third energy compensation capacitor 521, a third discharge resistor 522, a sixth switch 523, a first inductor 524, a fourth discharge resistor 525 and a seventh switch 526, wherein the third discharge resistor 522 and the sixth switch 523 are connected in series, the branch connected in series by the third discharge resistor 522 and the sixth switch 523 is connected in parallel with the third energy compensation capacitor 521, the first end of the first inductor 524 is electrically connected with the first end of the saturable reactor 30 and the first end of the first discharge unit 12 respectively, the second end of the first inductor 524 is electrically connected with the first end of the fourth discharge resistor 525, and the two ends of the seventh switch 526 are electrically connected with the second end of the fourth discharge resistor 525 and the first end of the third energy compensation capacitor 521 respectively. Through the combined use of the third energy compensation capacitor 521 and the first inductor 524, a stable preset current can be established in the saturable reactor 30, the energy release path when the power assembly is triggered is ensured, the establishment and maintenance of the reactor preset current and the rapid release of the current after triggering are realized, and the overall accuracy and reliability of the test are improved.

[0039] The charging device mentioned above can select a constant current source at low voltage, and can select an impulse voltage generator at high voltage and extra-high voltage.

[0040] The equivalent method of the above-mentioned equivalent circuit is divided into three stages:

[0041] Stage 1 is the pre-charging stage: the power assembly is not triggered, the first charging device charges the first energy compensation capacitor, the second charging device charges the second energy compensation capacitor, and the third charging device charges the third energy compensation capacitor;

[0042] Stage 2 is the saturable reactor current establishment stage: the sixth switch is opened, the third energy compensation capacitor discharges to the saturable reactor through the first inductor, and the required preset current is established and maintained before the power assembly is triggered;

[0043] Stage 3 is the trigger discharge stage: the power assembly is triggered and opened, the first energy compensation capacitor connected in parallel across the single valve discharges to the power electronic device through the saturable reactor, simulating the discharge process of the valve-type surge arrester; at the same time, the second energy compensation capacitor connected in parallel across the power assembly discharges directly to the power assembly through the second discharge resistor, simulating the discharge process of the device-level surge arrester.

[0044] Taking a 120kV hybrid controllable commutation converter as an example, the device-level surge arrester and the valve-type surge arrester are obtained by simulation or calculation to obtain the shunt curve diagram, as shown in Figure 5The device arrester establishes a current of 2000 A, the valve arrester establishes a current of 1000 A, and the saturable reactor has the same current as the device arrester, which also establishes a current of 2000 A, which has caused the saturable reactor to reach a saturated state, presenting a small inductance, and the inductance value is about the hollow inductance value. Subsequently, the protection semiconductor device is triggered to be turned on, and the device arrester will directly transfer a current of 2000 A to the semiconductor device, while the valve arrester will transfer a current to the semiconductor device through the saturable reactor, and the semiconductor device (power electronic device) receives the current discharge of the device arrester and the valve arrester. The above fully embodies the non-periodic triggering process of the controllable commutation thyristor valve, and from the above analysis, it can be known that the process is completely different from the conventional commutation thyristor valve, mainly embodied in that: the current is not all established on the valve arrester, the device arrester and the valve arrester will produce a shunt, and the distribution of the current is related to the parameters of the valve and the device arrester. Before the semiconductor device is turned on, the saturable reactor has established the same current as the device arrester, and the size of the current will affect the effect of the saturable reactor on limiting the current rising rate. Since the device arrester is directly connected in parallel across the device, the saturable reactor can only limit the current transfer of the valve arrester, and cannot affect the current transfer of the device arrester.

[0045] The saturable reactor has established a current before the power assembly is turned on, which is simulated by the current establishment module. First, the third charging device charges the third energy compensation capacitor through the fifth switch. After the charging is completed, the sixth switch is opened, and the third energy compensation capacitor discharges to the saturable reactor through the fourth discharging resistor and the first inductor, so that the saturable reactor can be maintained at Figure 5 The device arrester establishes a current. Finally, the third discharging resistor and the sixth switch can complete the discharging of the third energy compensation capacitor.

[0046] By adjusting the charging voltage of the first charging device and the second charging device, the charging current size is controlled to ensure that the first energy compensation capacitor and the second energy compensation capacitor are charged to the target voltage. After the third energy compensation capacitor is charged, the power assembly is triggered to be turned on, and the second switch and the third switch are opened to ensure that the first energy compensation capacitor discharges to the power assembly through the saturable reactor, and the second energy compensation capacitor discharges to the power assembly through the second discharging resistor.

[0047] The device arrester is usually directly connected across the expensive device such as IGCT, which is used to protect the device from overvoltage damage. The second energy compensation capacitor and the second discharging resistor connected in series with the second energy compensation capacitor can independently adjust the peak value, steepness and energy of the current discharged to the device. In addition, the current establishment module in the circuit can simulate the existing current of the saturable reactor before the device is turned on, so that the equivalent circuit can accurately reproduce the action characteristics of the device arrester and the stress on the device.

[0048] In some embodiments, to further improve the safety and stability of the non-periodic trigger test circuit, a temperature sensor is arranged at the energy compensation capacitor or discharge resistor to monitor the temperature change of the key parts in real time. The temperature sensor can be in the form of a thermocouple, a thermistor or an optical fiber temperature sensor, and can work reliably in a high-voltage electromagnetic environment. In order to realize closed-loop control of temperature, a cooling system and a protection system are arranged in the equivalent circuit. The cooling system can include a forced air cooling device or a liquid cooling circulation device, which is used to automatically adjust the flow rate or air speed of the cooling medium according to the detected temperature signal. When the temperature sensor detects that the local temperature exceeds the preset threshold, the control unit automatically increases the operating power of the cooling system to quickly remove the local heat, so that the system temperature is maintained within the set range. If the temperature continues to rise and reaches a safety threshold, the protection system will be triggered. The protection system can include a fast circuit breaker, a bypass loop or a controllable switch unit. When the protection system is started, the control unit sends an instruction according to the temperature signal, so that the main loop current is quickly transferred to the protection branch or directly cut off, thereby preventing the capacitor, discharge resistor and power electronic devices from being damaged due to overheating. By introducing the integrated design of temperature monitoring, cooling and protection into the test circuit, the application can realize the thermal management and over-temperature protection of the key components such as the energy compensation capacitor and the discharge resistor, which not only improves the safety and repeatability of the non-periodic trigger test, but also guarantees the accuracy of the test results and the long-term reliable operation of the circuit system.

[0049] In some embodiments, to adapt to different test voltage levels and safety isolation requirements, the non-periodic trigger test circuit of the present application can increase isolation switches at the relevant positions that need to be isolated. The isolation switches can be in the form of mechanical high-voltage isolation switches, vacuum circuit breakers, gas-insulated isolation devices, or solid-state isolation switches, etc., used to achieve electrical isolation between different parts of the test circuit, prevent interference of the high-voltage loop on the low-voltage measurement, control and trigger system, and improve the operation safety and reliability of the test system. Although the specific positions of the isolation switches are not explicitly drawn in the drawings, based on the circuit topology of the present application, isolation devices can be set as needed according to different test voltage levels, test modes and control strategies. For example, an isolation switch can be set between the energy storage capacitor and the main discharge circuit to cut off the energy storage branch before and after the test to prevent false triggering of discharge; an isolation switch can be set between the surge capacitor generator and the resistance circuit to control the discharge path and discharge rate; and an isolation device can also be arranged between the power input end and the control module to achieve live maintenance, test switching or rapid disconnection protection in abnormal state. In addition, the control mode of the isolation switch can be manual operation, remote electric control or automatic locking linkage according to system requirements. When voltage overrun, temperature anomaly or system short circuit risk is detected, the isolation switch can be automatically actuated by the protection system to isolate the fault branch from the main circuit, thereby preventing the spread of local faults and ensuring personnel and equipment safety. Through the above design, the present application realizes the hierarchical isolation and flexible configuration of the test circuit, significantly improving the electrical safety and maintenance convenience of the system.

[0050] In another extended embodiment, to adapt to different test current amplitudes, energy levels and equivalent discharge requirements, the discharge branch of the present application can realize current expansion by parallel connection of multiple-capacitor discharge circuits. By parallel connection of two or more groups of capacitor discharge units in the main discharge branch, flexible configuration can be realized according to the required simulated current waveform, discharge duration or energy level to meet the parameter requirements of different non-periodic trigger tests of converter valves. Each parallel discharge unit can include an independent discharge capacitor, discharge resistor and trigger switch, and the multiple discharge units can be connected through voltage balancing resistors or synchronous trigger control circuits to realize balanced and synchronized discharge process, avoiding voltage imbalance or current concentration caused by parameter deviation. Further, the parallel discharge circuit can be configured as an optional modular structure, and by adjusting the number of modules or the conduction state of the control switch, fine hierarchical adjustment of the discharge current can be realized. The present application not only can flexibly adapt to test requirements of different voltage levels and energy levels, but also significantly improves the scalability and repeatability of the test circuit. In different test scenarios, users can parameterize the capacitor capacity, number of parallel branches and trigger mode according to test requirements to realize precise current simulation and energy release control. Whether it is to increase isolation switches on the basis of the original single discharge circuit structure or to realize controllable current output by expansion parallel connection, it all belongs to the protection scope of the present application.

[0051] In some embodiments, the non-periodic trigger test circuit of the present application is not only applicable to the test scenario of the hybrid controllable commutation converter, but also can be applied to the non-periodic trigger test of the conventional converter valve by controlling the switch state of each module in the circuit. Specifically, by controlling the switch state of the current establishment module and the second simulation module (for example, not putting the charge and discharge units in the current establishment module and the second simulation module), the circuit can be flexibly switched between different operating modes. When only the first simulation module is enabled, the circuit can be equivalent to the non-periodic trigger test structure of the conventional converter valve; when the pre-set current is not established by the saturable reactor at the non-periodic trigger moment, only the first simulation module and the second simulation module can be controlled, and the two modules are simultaneously put into operation to meet the non-periodic trigger test structure of the hybrid converter valve under different operating parameters. This way realizes the compatible test of different converter valve topologies and different parameter settings on the same test platform, significantly improving the reusability and adaptability of the test equipment. Therefore, the test circuit of the present application has high modularity and universality in structure, and can realize the non-periodic trigger test of various converter valve topologies (including conventional LCC converter valve and hybrid converter valve) by controlling the logic switching, which not only meets the diversified experimental needs, but also reduces the cost of repeated construction of equipment.

[0052] According to another aspect of the embodiments of the present application, a control method of an equivalent circuit of a controllable commutation converter is provided, which is used to control the equivalent circuit of the controllable commutation converter, as shown in Figure 6 The control method comprises the following steps:

[0053] In step S1, a first charging unit of a first simulation module of the equivalent circuit is controlled to be turned on, so that the first charging unit charges a first discharging unit of the first simulation module.

[0054] Specifically, the first charging unit is composed of a first charging device, a first charging resistor and a first switch. By controlling the first switch, the high voltage generated by the first charging device can be applied to the first energy compensation capacitor to complete the charging process. The turning on of the second charging unit ensures that the second energy compensation capacitor of the second discharging unit can be charged to a specific voltage to simulate the discharge process of the device arrester under the non-periodic trigger working condition.

[0055] In step S2, a second charging unit of a second simulation module of the equivalent circuit is controlled to be turned on, so that the second charging unit charges a second discharging unit of the second simulation module.

[0056] Specifically, the second charging unit is composed of a second charging device, a fourth switch and a second charging resistor. By controlling the fourth switch, the high voltage generated by the second charging device can be applied to the second energy compensation capacitor to complete the charging process. The sequence relationship of the above charging process is not specifically limited.

[0057] Step S3, control the first discharge unit and the second discharge unit to open at the same time, make the first discharge unit discharge to the power component through the saturable reactor of the equivalent circuit to simulate the current leakage of the arrester parallel to the single converter valve in the controllable commutation converter, and make the second discharge unit discharge to the power component of the second simulation module to simulate the current leakage of the arrester parallel to the semiconductor device in the controllable commutation converter;

[0058] Specifically, the first discharge unit is composed of a first energy supplement capacitor and a second switch, and by controlling the opening of the second switch, the energy stored in the first energy supplement capacitor is released to the power component through the saturable reactor to simulate the current leakage process of the valve arrester. The opening control of the second discharge unit realizes the simulation of the current leakage process of the device arrester. Specifically, the second discharge unit is composed of a second energy supplement capacitor, a third switch and a second discharge resistor, and by controlling the opening of the third switch, the energy stored in the second energy supplement capacitor is released to the semiconductor device through the second discharge resistor to simulate the current leakage process of the device arrester. The current leakage processes of the device arrester and the valve arrester are carried out at the same time, and the non-periodic triggering current leakage condition is simulated at the same time. This cooperative control makes the test results truly reflect the current transfer process of the valve arrester and the device arrester of the hybrid controllable commutation converter when the hybrid controllable commutation converter is subjected to non-periodic triggering.

[0059] Through the control of the equivalent circuit by the above control method, when the power component in the second simulation module is not triggered, the first charging unit of the first simulation module is used to charge the first discharge unit of the first simulation module, and after the charging is completed, the first discharge unit of the first simulation module discharges to the power component when the power component is turned on, simulating the discharge of the valve arrester. The second charging unit and the second discharge unit in the second simulation module are respectively connected in parallel with the power component, which can independently control the charging and discharging of the device arrester to provide accurate simulation of the device arrester. In this way, the discharge process of the device arrester can be synchronized with and independent of the process of the valve arrester, improving the overall controllability and accuracy of the test. Through two independent and cooperative modules, the discharge characteristics of the device arrester and the discharge characteristics of the valve arrester are realized, which can ensure that each module can accurately match the actual working condition, avoid the deviation of the test results caused by the mutual influence between the modules in the traditional test method, effectively reproduce the actual stress condition of the hybrid controllable commutation converter in the non-periodic triggering process, and significantly improve the fidelity and reliability of the test results.

[0060] Step S4, after the current transfer simulation in the non-periodic triggering is completed, if the electricity of the discharge unit in the second simulation module has not been completely released, the sixth switch of the current establishment module can be opened to make the discharge capacitor of the second simulation module directly discharge through the third discharge resistor.

[0061] The voltage and current established by the saturable reactor, the device type arrester and the valve type arrester in the non-periodic triggering mode of the converter valve, and the discharge rate in the discharge process can complete the calculation of various parameters in the experimental circuit (including but not limited to the saturation time of the saturable reactor, the value of the first energy compensation capacitor, the value of the second energy compensation capacitor and the second discharge resistor), so as to realize the accurate simulation of the different current transfer rates, current amplitudes, current transfer times and discharge energy distribution of the valve type arrester and the device type arrester of the controllable commutation converter.

[0062] In some optional embodiments, the equivalent circuit further comprises a current establishment module, the current establishment module comprising a third charging unit and a third discharging unit, wherein the first end of the third discharging unit is electrically connected to the first end of the saturable reactor and the first end of the first discharging unit respectively, the second end of the third discharging unit is electrically connected to the second end of the saturable reactor and the second end of the third charging unit respectively, the first end of the third charging unit is electrically connected to the third discharging unit, and the control method further comprises:

[0063] controlling the third charging unit to be turned on so that the third charging unit charges the third discharging unit, and the third discharging unit after being charged is used to establish a preset current for the saturable reactor in the turned-on state;

[0064] Specifically, the turning-on control of the third charging unit ensures that the third energy compensation capacitor of the third discharging unit can be charged to a specific voltage to simulate the actual working condition that the reactor has established a preset current before the device is triggered. Specifically, the third charging unit is composed of a third charging device, a fifth switch and a third charging resistor. By controlling the fifth switch, the voltage generated by the third charging device can be added to the third energy compensation capacitor to complete the charging process. Each charging unit can be independently controlled, which can more accurately reproduce the residual voltage characteristics of the arrester and the current control characteristics of the reactor in the actual working condition, and significantly enhances the simulation accuracy of the test circuit.

[0065] Before the first discharging unit of the first simulation module of the equivalent circuit and the second discharging unit of the second simulation module of the equivalent circuit are turned on, the third discharging unit is controlled to be turned on so that the third discharging unit discharges to the saturable reactor to establish a preset current for the controllable commutation converter.

[0066] Specifically, the third discharging unit is composed of a third discharging capacitor, a third discharging resistor, a sixth switch and a first inductor. By controlling the turning-on of the sixth switch, the energy stored in the third discharging capacitor is released through the first inductor and the saturable reactor to establish a preset current.

[0067] The current establishment module can ensure that preset current is set in the equivalent circuit before the power electronic device (semiconductor device in the power assembly in the application) is triggered, the pre-charging state of the reactor of the controllable commutation converter in the actual working condition can be simulated, and the accuracy and fidelity of the test are improved.

[0068] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present application.

[0069] It should be further understood that the terms "comprise", "comprising", or any other variant thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles, or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles, or devices. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of other identical elements in the process, method, article, or device that includes the element.

[0070] The above is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An equivalent circuit of a controllable commutated converter, characterized in that, include: The system comprises a first analog module, a second analog module, a saturated reactor, and a power component, wherein the power component includes semiconductor devices. The first simulation module includes a first charging unit and a first discharging unit. The first end of the first charging unit is electrically connected to the first discharging unit, and the first end of the first charging unit is electrically connected to the second end of the first discharging unit. The first end of the first discharging unit is electrically connected to the first end of the saturated reactor. The first charging unit is used to charge the first discharging unit, and the first discharging unit is used to discharge to the second simulation module through the saturated reactor to simulate the leakage current of the surge arrester connected in parallel across a single converter valve in a controllable commutation converter. The second simulation module includes a second charging unit and a second discharging unit. The power component is connected in parallel with the second charging unit and the second discharging unit. The first end of the power component is electrically connected to the first end of the second discharging unit and the second end of the saturated reactor, respectively. The second end of the power component is electrically connected to the second end of the first discharging unit, the second end of the second discharging unit, and the second end of the second charging unit, respectively. The first end of the second charging unit is electrically connected to the second discharging unit. The second charging unit is used to charge the second discharging unit, and the second discharging unit is used to discharge to the semiconductor device to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the converter valve.

2. The equivalent circuit according to claim 1, characterized in that, The first charging unit includes a first charging device and a first switch. The two ends of the first charging device are electrically connected to the first end of the first switch and the second end of the first discharging unit, respectively. The second end of the first switch is connected to the first end of the first discharging unit.

3. The equivalent circuit according to claim 1, characterized in that, The first discharge unit includes a first energy replenishing capacitor, a second switch, and a first discharge resistor. The first end of the first energy replenishing capacitor is connected to the first end of the first charging unit and the first end of the first discharge resistor, respectively. The second end of the first energy replenishing capacitor is electrically connected to the second end of the first charging unit, the second end of the power component, and the second end of the second discharge unit, respectively. The second end of the second switch is electrically connected to the first end of the saturated reactor.

4. The equivalent circuit according to claim 1, characterized in that, The second discharge unit includes a second energy replenishing capacitor, a third switch, and a second discharge resistor. The first end of the second discharge resistor is electrically connected to the first end of the power component and the second end of the saturated reactor, respectively. The second end of the second discharge resistor is connected to the first end of the third switch. The second end of the third switch is connected to the first end of the second energy replenishing capacitor and the first end of the second charging unit, respectively. The second end of the second energy replenishing capacitor is electrically connected to the second end of the power component and the second end of the second charging unit, respectively.

5. The equivalent circuit according to claim 1, characterized in that, The second charging unit includes a second charging device and a fourth switch, wherein the two ends of the fourth switch are electrically connected to the second discharging unit and the first end of the second charging device, respectively, and the second end of the second charging device is electrically connected to the second end of the second discharging unit and the second end of the power component, respectively.

6. The equivalent circuit according to claim 1, characterized in that, The equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first end of the third discharging unit is electrically connected to the first end of the saturated reactor and the first end of the first discharging unit, respectively. The second end of the third discharging unit is electrically connected to the second end of the saturated reactor and the second end of the third charging unit, respectively. The first end of the third charging unit is electrically connected to the third discharging unit.

7. The equivalent circuit according to claim 6, characterized in that, The third charging unit includes a third charging device and a fifth switch. The two ends of the fifth switch are respectively connected to the first end of the third charging device and the third discharging unit. The second end of the third charging device is electrically connected to the second end of the third discharging unit and the second end of the saturated reactor.

8. The equivalent circuit according to claim 6, characterized in that, The third discharge unit includes: a third energy-replenishing capacitor, a third discharge resistor, a sixth switch, a first inductor, a fourth discharge resistor, and a seventh switch. The third discharge resistor and the sixth switch are connected in series, and the branch formed by the series connection of the third discharge resistor and the sixth switch is connected in parallel with the third energy-replenishing capacitor. The first end of the first inductor is electrically connected to the first end of the saturated reactor and the first end of the first discharge unit, respectively. The second end of the first inductor is electrically connected to the first end of the fourth discharge resistor, respectively. The two ends of the seventh switch are electrically connected to the second end of the fourth discharge resistor and the first end of the third energy-replenishing capacitor, respectively.

9. A control method for the equivalent circuit of a controllable commutated converter, characterized in that, The control method for controlling the equivalent circuit of the controllable commutated converter according to any one of claims 1 to 8 includes: The first charging unit of the first analog module of the equivalent circuit is turned on so that the first charging unit charges the first discharging unit of the first analog module. The second charging unit of the second analog module of the equivalent circuit is turned on, so that the second charging unit charges the second discharging unit of the second analog module. The first discharge unit and the second discharge unit are controlled to be turned on simultaneously, so that the first discharge unit discharges to the power component through the saturated reactor of the equivalent circuit to simulate the leakage of the surge arrester connected in parallel across a single converter valve in the controllable commutation converter, and the second discharge unit discharges to the power component of the second simulation module to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the controllable commutation converter.

10. The control method according to claim 9, characterized in that, The equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first terminal of the third discharging unit is electrically connected to both the first terminal of the saturated reactor and the first terminal of the first discharging unit. The second terminal of the third discharging unit is electrically connected to both the second terminal of the saturated reactor and the second terminal of the third charging unit. The first terminal of the third charging unit is electrically connected to the third discharging unit. The control method further includes: The third charging unit is controlled to turn on so that it charges the third discharging unit. After being charged, the third discharging unit is used to establish a preset current for the saturated reactor when it is turned on. Before the first discharge unit of the first analog module of the equivalent circuit and the second discharge unit of the second analog module of the equivalent circuit are turned on, the third discharge unit is turned on so that the third discharge unit discharges to the saturated reactor and establishes a preset current for the controllable commutator.

Images